This document has two purposes:  To present lessons learned during implementation of the Gateway to Kindergarten Readiness initiative; and to provide insights and effective practices for use by stakeholders working to align early care and education (ECE) and public education systems. This Knowledge Document aims to tell both of these stories -- the story of the intervention and the story of systems alignment -- in a way that is helpful for practitioners working in both arenas. Therefore, the document is organized into two sections. The first section is based on multi-year formative and summative evaluation findings and tells the story of the GTKR initiative, including successes, barriers, and lessons learned for future programming. The second section focuses on the larger issue of systems alignment and discusses the local context (including COVID-19 learnings and considerations), as well as a recommended framework and strategy for future ECE systems alignment activities. (author abstract)